In recent years, use of computer communication networks or information networks represented by the Internet, has come into wide and popular use, and has been increasing without distinction among ordinary households, enterprises, and the like. The most common use form is such that personal computers and the like are directly connected with LAN cables, or connected by way of wireless to establish a LAN (Local Area Network), which allows access from the computers in the LAN to a network such as the Internet. In such circumstances, when a LAN cable is used, the cable is routed in a house or an office, causing an obstruction to walking or an appearance problem. Whereas, when wireless LAN is used, communication is performed using radiation of electric waves, which causes security problems such as information leakage and an unauthorized access.
Under such circumstances, the fact that these problems can be solved by making communication means two-dimensional, and using a two-dimensional communication medium is shown in Patent Document 1 (JP-A-2004-7448) and Patent Document 2 (JP-A-2006-19979).
Whereas, in recent years, office security has received attention, so that information networks of an office environment have been upgraded. In a conference room or a discussion space, prevention of information leakage has become valued, creating a demand for space with high security in an office. On the other hand, a free-address office also has attracted great attention. One can hold one's access environment even upon moving, which enables control of the individual ID, and acquisition/control/display of the positional information.
In such circumstances, setting of a communication sheet structure on a top of a desk in a conference room or one's own room in an office is largely useful for construction of an office network.
Other than these, there are ideas in which RFID tags and this communication sheet structure are combined to perform inventory control and physical distribution management; and in which this communication medium is set over the entire wall surface or the entire floor surface for use as a sensor sheet.
Such ideas of use in combination with RFID tags, and use in the form with a larger area such as the wall entire surface or the floor entire surface require further enhancement of the transmission efficiency of the communication medium, and improvement of the communication performances. Further, there is a demand for a communication medium with higher durability from the viewpoint of practical utility.
On the other hand, for the foregoing uses, being handy to carry is desirable in consideration of the convenience of a constructor and a user. Particularly, the communication medium to be set over the entire wall surface or the entire floor surface increases in area as described above. Therefore, it is required to be carried or stored in the rolled form. However, with the conventionally proposed communication media, no specific proposals have not been made on this point at all. The inventors attempted to form communication media with various materials. However, they found that there were problems such as difficulty in winding this in a roll form, becoming wrinkled upon attempting to forcedly wind this in a roll form, and reduction of communication performances.
[Patent Document 1] JP-A-2004-7448
[Patent Document 2] JP-A-2006-19979